Method of grinding antifriction needle bearings



Dec. 1, 1936. E. BENEDEK r 2,062,803.

METHOD OF GRINDING ANTIFRICTION NEEDLE BEARINGS Filed Jan. 27, 1933 Patented Dec. 1, i936 METHOD OF GRINDING ANTHRICTION NEEDLE BEARINGS Elek Benedek, Mount Gilead, Ohio Application January 27, 1933, Serial No. 653,873

8 Claims.

This invention relates to a method of finishing antifriction bearing rollers and particularly cylindrical or tapered needle rollers, that is, rollers of relatively small size as compared to conventional antifriction bearing rollers. Such needles are shown and claimed in my prior application Ser. No. 641,186, filed November 4, 1932, and in a separate application Ser. No. 23,880, filed May 28, 1935, the latter being a division and continuation of the present application.

The principal object is to provide a method by which the necessary apparatus for grinding the rollers may be greatly simplified while producing rollers of greater uniformity in size and finish.

A further object is to provide a grinding process or method by which the number of finished pieces per given time may be greatly increased without sacrifice of accuracy.

A further object is to provide a new and improved centerless grinding method applicable principally to forming needle rollers and the like.

The invention consists principally in feeding the roller stock or blanks between a pair of oppositely moving abrasive surfaces having space enough between them to accommodate several rollers at the same time in grinding position with respect to both surfaces and further in the provision of such peripheral space between the surfaces that the blanks are finished to exactly the desired diameter successively and automatically ejected from between the abrasive surfaces in the direction of feeding the blanks to the grinding surfaces. Various refinements of the above outlined process or method will appear in the following description relating to the accompanying drawing wherein exemplary apparatus for carrying out the method is shown. The essential novel characteristics of the invention are summarized in the claims.

Referring to the drawing:

Fig. 1 shows diagrammatically a pair of grinding wheels in operation on the roller stock;

Fig. 2 is a plan view of the arrangement shown in Fig. 1, showing the substantially finished roller between the wheels;

Figs. 3 and 4 are views, substantially corresponding to Figs. 1 and 2 respectively, of an adaptation of the apparatus for forming tapered bearing rollers or needles; and

Fig. 5 is a more complete view illustrating in diagrammatic vertical section-the complete grinding apparatus.

The needle rollers to which the process is particularly adapted are characterized principally in that the rollers are small and their length is from five to ten times their diameter. It is highly important in the manufacture of such needle bearing rollers that all the. needles be made as nearly as possible the same size so as to properly distribute the load on all the rollers in load carrying position in a single bearing assembly. With the manufacture of such accurately formed rollers in view I provide, for example, (see Figs. 1 and 2) a pair of absolutely parallel grinding wheels such as 31 and 38 mounted on parallel shafts 39 and 40 carried in a suitable rigid support (not shown). The support may, of course, be provided for relative adjustment of the wheels toward and away from each other.

The wheel axes are preferably disposed in a common horizontal plane and, in the case of forming cylindrical needles, the working surfaces of the wheels are absolutely cylindrical and spaced, as previously mentioned, a distance corresponding to the desired diameters of the needles. The wheels are rotated'in opposite directions and preferably insuch manner that one of the wheels-say 3'lhas its working surface moving downwardly (see arrows 43) toward the final grinding throat (minimum space between wheels) somewhat faster than the working surface of the other wheel moves upwardly from the throat (see arrows 65) This speed relationship between grinding wheels .is not new except .in connection with the present process.

Suitable means are provided to feed the blanks-say forged and caseor pack-hardened metal stock of the required length-by gravity into the open space above the throat, such means maintaining the blanks parallel with each other at the time of being discharged into said space. A work blank 4| is shown as occupying the upper portion of the space, Fig. 1, this blank being greatly exaggerated in 'size for illustration only:

The peripheral travel of the wheels rotates the blanks as indicated by the arrow 46 and the speed differential between the abrasive surfaces of the wheels results in a grinding operation being performed on the stock so positioned and meanwhile the somewhat greater speed of the downwardly moving surface tends to assist the constant force of gravity in urging the blank toward the throat. The substantially finished piece at 42, when reduced by abrasive contact with the wheels tothe smallest peripheral transverse dimension of the throat, drops through automatically.

and eject the same automatically when finished to the proper size. However, to the best of my knowledge, this process is new in finishing cylindrical or tapered rollers or needle rollers. It is also new to support the several pieces of roller stock solely by the wheel surfaces themselves and in contact therewith without guides. It is also new to accomplish .this simultaneous grinding, on a plurality of blanks with wheels rotating at different speeds for accelerating the grinding operation particularly during the final finish on the blanks. It is particularly new to provide space to receive a number of blanks between the grinding wheels and to feed a plurality of blanks at a time to the grinding surfaces, so that by abrasive contact of the several blanks with one or the other or both of the wheels, the grinding operation is performed much faster than formerly, while producing rollers of identical diameters.

The oncoming blanks in contact with respective grinding surfaces of the wheels and with the preceding blank or blanks (nearer the throat) maintain the alignment of the stock with the wheel surfaces and coact with the cooling or lubricating medium in eliminating chatter or excessive vibration of the work being ground. Thus, in place of the usual steady-rest or support heretofore considered necessary for accurate grinding operations such as described, I substitute the steadying effect of the oncoming blanks and the vibration dampening effect of the fluid medium, meanwhile grinding and reducing the oncoming blanks toward the dimensions necessary to finally finish the pieces, greatly speeding up the operation as a whole. by maintaining a true continuous grinding process. In connection with this method a suitable cooling and lubricating medium is employed as in practically all grinding processes and this medium acts as a dampening force against excessive vibration and oscillation of the blanks during the grinding process, hydraulically floating the individual blanks in a capillary fiuid carrier. The semi-finished blanks as well as those substantially completed (very near the throat) are actually fioated in the cooling or lubricating medium and restrained thereby against such vibration or chattering as might cause fiat sided pieces.

Referring now to Figs. 3 and 4, the illustrated process is identical with that just described except that, of course, the grinding wheels are so faced relative to each other that the grinding throat is tapered in cross section rather than rectangular.

Referring to Fig. 5', this shows the grinding wheels at 53 and 54 supported on a suitable base or frame 58. Surmounting the frame and suitably supported in any convenient manner is a hopper 55 for the blanks. The lower or blank supporting walls of the hopper are so arranged that a plurality of blanks may be discharged through the opening where they would naturally partially fill the space above the grinding throat so that a number of blanks may come into contact simultaneously with both wheels (not illustrated) The cooling or lubricating medium may be fed through the hopper so as to follow the blanks into grinding position as a capillary dampening and carrying medium and ,so as to properly lubricate the abrasive faces of the wheels. The operation of ejecting the finished rollers from between the wheels is illustrated in Fig. 5, 56 indicating a roller dropping from the throat into a pile of finished rollers supportedsay on a convenient tray 51. The finished pieces may, of course, be

lapped, polished etc. after grinding following conventional practice.

It is contemplated that the wheel speeds may be adjusted and varied to suit the work being ground, certain speeds being found better for some steel alloys-and other speeds for other alloys. The wheel 54, as shown, is driven by a variable belt (diagrammatically indicated at 59) and I may also use a variable speed hydraulic motor for driving one or both wheels and accurately governing the wheel speed with relation to the work.

Having fully described my invention, what I claim is new and desire to secure by Letters Patent, is:

1. The continuous method of grinding rollers comprising simultaneously introducing a plurality of roller blanks between a pair of relatively r0- tating grinding elements having operating peripheral surfaces spaced apart a distance corresponding to the desired diameter of the finished rollers, at least one of said surfaces being a grinding surface supporting a plurality of the roller blanks so introduced by the converging peripheral surfaces so that grinding of a plurality of rollers is accomplished simultaneously and so that the less finished blanks hold the more nearly finished blank or blanks in parallelism with the surfaces and with each other, and successively discharging the finished rollers one by one from between the surfaces in a direction away from the oncoming blanks and transversely to the axes of the finished by gravity toward the final grinding throat,

whereby a plurality of blanks are being rough ground while the leading blank is being finish ground, and discharging the finished blanks successively and by gravity from the final grinding throat.

3. The method of grinding rollers comprising introducing roller blanks from and in a substantially vertical direction between a pair of horizontally spaced peripheral rotating operating surfaces, at least one of said surfaces being a grinding surface, maintaining the space between the surfaces such that a plurality of said blanks contact with respective surfaces for simultaneous rough and finish grinding operations thereon, and discharging the finished blanks by gravity from between the surfaces when the blanks are reduced in diameter to the space between the surfaces.

4. The method of grinding bearing rollers comprising introducing a plurality of roller blanks from and in a substantially vertical direction, between a pair of horizontally spaced relatively moving converging operating surfaces, at least one of said surfaces being a grinding surface, maintaining a plurality of the blanks in simultaneous working contact with one or the other of the surfaces and in parallelism with each other by mutual contact between a plurality of said blanks, and successively discharging the finished blanks from between the surfaces when reduced in diameter to'the width of peripheral spacing of the surfaces.

5. The method of grinding rollers comprising introducing a plurality of roller blanks between a pair of grinding wheels, said wheels having peripheral operating surfaces, at least one of said 7 surfaces being a grinding surface and said surfaces being peripherally spaced to form a grinding throat of a width corresponding to the desired diameter of the finished rollers, rotating the wheels in opposite directions'in such manner that the travel of one wheel surface toward the throat is faster than the surface travel of the other wheel surface away from the throat for maintaining an abrasive differential surface contact with the blanks while frictionally rotating the blanks when in contact with both surfaces, maintaining a blank receiving space between the surfaces sufiicient to receive such plurality of blanks in contact with respective wheel surfaces for initiating rotation of the blanks and to effect preliminary grinding of a plurality thereof prior to the blanks individually and simultaneously contacting with both surfaces, and finally successively discharging the finished rollers through the throat when reduced to the width thereof.

6. The method of grinding rollers comprising simultaneously introducing a plurality of roller blanks in substantially parallel position between a pair of peripheral grinding wheel surfaces rotating at different speeds and spaced apart radially of the wheels 9. distance corresponding to the desired diameter of the rollers at least one of said surfaces being a grinding surface, supporting and meanwhile grinding certain of the blanks by contact with respective said converging peripheral surfaces, meanwhile maintaining a constant feeding force on all the blanks in a direction toward the grinding throat of the surfaces whereby the blanks are moved toward said throat and finally finish ground to said diameter by contact with both surfaces, and automatically ejected one by one from between the surfaces when reduced to said diameter.

7. The continuous method of grinding rollers comprising continuously introducing free blanks between a pair of relatively rotating grinding eleterposed blanks toward said throat and succes-- sively discharging the finished rollers from the throat in a direction away from the oncoming blanks. I

8. The continuous method of grinding rollers comprising continuously introducing free blanks between a pair of relatively rotating grinding elements having operating surfaces spaced apart a distance corresponding'to the desired diameter of the finished rollers and providing a grinding throat, at least one surface being a grinding surface, supporting and maintaining in parallelism a plurality of free roller blanks so introduced simultaneously between the grinding surfaces and in cooperation therewith only by the grinding elements and by each other while in the grinding throat so that grinding of a plurality of blanks is accomplished simultaneously and less .finished blanks hold the more nearly finished blanks in position with respect to the surfaces, and the superposed blanks continuously urge the subterposed blanks toward said throat and successively discharging the finished rollers from the throat in a direction away from the oncoming blanks.

. ELEK BENEDEK. 

